Stress Analysis of Truck Chassis Using FEA - BE Project - ALL
PROJECT REPORT On STRESS ANALYSIS ON TRUCK CHASSIS USING FEA Submitted in partial fulfillment for the award of the degree Of BACHELOR OF TECHNOLOGY in MECHANICAL ENGINEERING By T. DEEPAK SARATHY (10203036) V. DILIPAN (10203040) G. KARTHIK (10203063) under the guidance of Mr. S. PRABHU, M.E., (Senior Lecturer, School of Mechanical Engineering) & Dr. M. SATHYA PRASAD, DGM (Advance Engg.,) , Ashok Leyland, Chennai
FACULTY OF ENGINEERING AND TECHNOLOGY SRM UNIVERSITY (under section 3 of UGC Act,1956) SRM Nagar, Kattankulathur – 603 203 Kancheepuram Dist
Certified that this project report “STRESS ANALYSIS ON TRUCK CHASSIS USING FEA ”
“T. DEEPAK SARATHY (10203036), V. DILIPAN (10203040) and G. KARTHIK (10203063)” who carried out the project work under my supervision.
DEAN GUIDE School of Mechanical Engineering
INTERNAL EXAMINER EXAMINER
ACKNOWLEDGEMENT In the course of our project, we are indebted to so many people who have contributed for making this project a great success. We would like to express our heartfelt gratitude to our Dean Dr.Krishnan (School of mechanical Engineering SRMIST) for giving us this opportunity to do this project. We express our sincere gratitude to M/S ASHOK LEYLAND Private Limited for encouraging us to carry on this assignment. We owe our thanks to Dr.M.Sathyaprasad,
DGM (Advance Engg.,) for his guidance
throughout this project. We would like to thank our internal guide Mr.Prabhu (Senior Lecturer SRMIST) for his support, which helped us to complete this project successfully. We would like to express our sense of gratitude to all our college faculties for their timely help and valuable guidance in the course of the project. We are indebted to our parents for having supported us in all our endeavors…..
In this project, stress analysis of a truck chassis was performed through FEA. The truck chassis was modeled using PRO/E and the commercial finite element package ANSYS was used to solve the problem. The joint area with the max stress was identified using the above software package. In order to achieve a reduction in the magnitude of stress near the riveted joints area, local plates were introduced .
LIST OF CONTENTS
CHAPTER NO. NO
LIST OF FIGURES
LIST OF TABLES
LIST OF GRAPHS
1.1 Importance of connections
1.2 Stress Analysis
1.3 Finite Element Analysis
2.1.1 Sketcher Modes
2.1.2 Modeling tools
2.1.3 Assembly Constraints
2.1.4 Constrain orientation assumptions
2.1.5 Common exchange specifications
2.2 ANSYS 2.2.1 General Analysis Procedure
2.2.2 Structural Analysis
18.104.22.168 Types of Structural Analysis
22.214.171.124 Steps in a Structural Analysis
2.2.3 Benefits 3.
TRUCK AND CHASSIS
3.1 Different parts of a truck
3.2 Function of chassis
3.3 Parts of chassis
3.4 Riveting Operation in a truck chassis
3.5 Loads acting on a chassis
3.6 Material Data of the chassis
MODELING AND MESHING
4.1 PRO/E Model
4.2 Meshed Model
5.1 Load Applied on the model
5.2 Stress Distribution across joint areas
5.2.1 Stress distribution across joint 1
5.2.2 Stress distribution across joint 2
5.2.3 Stress distribution across joint 3
5.2.4 Stress distribution across joint 4
5.2.5 Stress distribution across joint 5
5.2.6 Stress distribution across joint 6
RESULTS AND DISCUSSION
LIST OF FIGURES FIGURE NO.
PAGE NO 3.1
Different Parts of a truck
Parts of a truck chassis frame
Installation of a riveter
Riveting Operations on a truck chassis
Pro/E model of chassis
Meshed model of chassis
Zoomed view of meshed model
Load Applied on the chassis
Zoomed view of the applied load
Stress distribution at joint 1 for nominal loading
Stress distribution at joint 1 for maximum loading 39
Stress distribution at joint 2 for nominal loading
Stress distribution at joint 2 for maximum loading 41
Stress distribution at joint 3 for nominal loading
Stress distribution at joint 3 for maximum loading 43
Stress distribution at joint 4 for nominal loading
Stress distribution at joint 4 for maximum loading 45
Stress distribution at joint 5 for nominal loading
Stress distribution at joint 5 for maximum loading 47
Stress distribution at joint 6 for nominal loading
Stress distribution at joint 6 for maximum loading 49
Gap at Joint 5
Introduction of local plates at joint 5
LIST OF TABLES
Stress distribution across various joint areas
LIST OF GRAPHS FIGURE NO.
PAGE NO 6.1 Stress distribution across joint areas for nominal loading condition 50 6.2 Stress distribution across joint areas for maximum loading condition 51
CHAPTER 1 INTRODUCTION 1.1 IMPORTANCE OF JOINTS: Many engineering structures and machines consist of components suitably connected through carefully designed joints. In metallic materials, these joints may take a number of different forms, as for example welded joints, bolted joints and riveted joints. In general such joints are subjected to complex stress states under loading since the joints are quite complex in nature there would manifest severe stress discontinuities that cannot be calculated using closed form solutions it is in such situations finite element analysis lends itself as an indispensable tool. Good design of connections is a mixture of stress analysis and experience of the behavior of actual joints; this is particularly true of connections subjected to repeated loads. 1.2 STRESS ANALYSIS: Stress analysis is an engineering discipline that determines the stress and strain in materials and structures subjected to static or dynamic forces or loads. The aim of the analysis is usually to determine whether the element or collection of elements, usually referred to a structure, can safely withstand the specified forces. This is achieved when the determined stress from the applied force(s) is less than the allowable strength, or fatigue strength the material is known to be able to withstand, though ordinarily a safety factor is applied in design.
A key part of analysis involves determining the type of loads acting on a structure, including tension, compression, shear, torsion, bending, or combinations thereof such loads. Sometimes the term stress analysis is applied to mathematical or computational methods applied to structures that do not yet exist, such as a proposed aerodynamic structure, or to large structures such as a building, a machine, a reactor vessel or a piping system. A stress analysis can also be made by actually applying the force(s) to an existing element or structure and then determining the resulting stress using sensors, but in this case the process would more properly be known as testing (destructive or non-destructive). In this case special equipment, such as a wind tunnel, or various hydraulic mechanisms, or simply weights is used to apply the static or dynamic loading. When forces are applied, or expected to be applied, repeatedly, nearly all materials will rupture or fail at a lower stress than they would otherwise. The analysis to determine stresses under these dynamically forced conditions is termed fatigue analysis and is most often applied to aerodynamic structural systems. 1.3 FEA Finite Element Analysis is a technique to simulate loading conditions on a design and determine the design’s response to those conditions. The design is modeled using discrete building blocks called elements. Each element has exact equations that describe how it responds to a certain load. The “sum of the response of all elements in the model gives the total response of the design”.
The finite element model, which has a finite number of unknowns, can only approximate the response of the physical system, which has infinite unknowns. It depends entirely on what we are simulation and the tools we use for the simulation. Guidelines are provided throughout this volume to perform various types of analysis.
WHY IS FEA NEEDED? :• To reduce the amount of prototype testing • Computer simulation allows multiple “what-if” scenarios to be tested quickly and effectively. • To simulate designs that are not suitable for prototype testing Example: Surgical implants, such as an artificial knee.
• The bottom line: -
Cost and Time savings.
Create more reliable, better-quality and competitive designs.
CHAPTER 2 SOFTWARE PACKAGES 2.1 PRO – E Pro/ENGINEER
development solution, which is developed by PTC-Parametric Technology Corporation a US based Company. This software enables designers and engineers to bring better products to the market faster. It takes care of the entire product development process, from creative concept through detailed
product definition to serviceability. Pro/ENGINEER delivers measurable value to manufacturing companies of all sizes and in all industries. With industry leading productivity tools such as promoting best practices in modeling techniques and ensuring compliance with your industry and company standards, Pro/ENGINEER is the gold standard in 3D CAD design. Integrated Pro/ENGINEER CAD/CAM/CAE solutions allow us to design faster than ever, while maximizing innovation and quality to ultimately create industry-winning products. And, because the applications are fully integrated, you can develop everything from concept to manufacturing within one application, with the confidence of knowing every design change will automatically be propagated to all downstream deliverables. Pro/ENGINEER is the solid modeler-it develops models as solids, allowing us to work in a three-dimensional environment. In Pro/ENGINEER, the models have volumes and surfaces areas. We can calculate mass properties from the geometry we create. As a solid modeling tool, Pro/ENGINEER is Feature Based Parametric Associative ¾ FEATURE BASED: Pro/ENGINEER is feature based. Geometry is composed of a series of easily understandable features. A feature is a smallest building block in a part model.
¾ PARAMETRIC: Pro/ENGINEER is a parametric (i.e.) it’s driven by parameters or variable dimensions. The geometry can be easily changed by modifying the dimensions. Here features are interrelated. Modifications of single feature propagate changes in other features as well, thus preserving design intent. ¾ ASSOCIATIVE: Pro/ENGINEER models are often combination of various
Pro/ENGINEER makes all these entities fully associative. That means if we make changes in certain level that will propagate in all levels. Now we shall explain the commands used to design our part from sketcher mode to the assembly 2.1.1
INTRODUCTION: Any geometry involving complex definitions and individual shapes requires sketch. Sketches are required for all types of protrusion and cuts. The word sketch is basically meant for sections, because the sketch represents the cross-section of any feature. Sketch is a two dimensional geometry, only when combined with other elements (example depth) it becomes a three dimensional feature. Now we shall see the various commands used in the sketcher mode in detail. ¾ LINE: Line command allows us to draw a line by specifying the end points. The Intent manager allows us to choose the options such as 2 points, parallel, perpendicular, tangent, 2 tangent, pnt/tangent horizontal, vertical.
¾ PARALLEL: Draws a line parallel to a selected linear entity. Select an existing entity for the direction of the line and then pick the start points and the end points ¾ PERPENDICULAR: Draws a line perpendicular to a selected linear entity. Select the existing entity for the direction of the line and then pick the start points and end points. ¾ TANGENT: This option facilitates to draw a line tangent from an entity to the next point. The selected entity should be an arc, ellipse, conic and spline .It prompts for end point, and then the line will be generated tangential to those entities. ¾ PNT/TANGENT: The line is drawn from a point to a tangent of an entity (Circle, arc, ellipse etc).Pick a point and selects the entity to which the line must be tangent. ¾ HORIZONTAL: Using this option we can generate horizontal lines. The end point of the line is taken as the start point of vertical chained vertical line. ¾ VERTICAL: Using this option we can generate vertical lines. The end point of the line is taken as the start point of vertical chained vertical line. ¾ CENTERLINE: Centerlines are used to define the axis of the revolution of a revolved feature, to define a line of symmetry within a section. It can be used as construction lines. Centerlines have infinite length and are not used to crate feature geometry.
¾ RECTANGLE: By picking up one vertex with the left mouse button and drag the rectangle to the desired size we can generate rectangle. The four lines of the rectangle are independent. We can handle them (trim, align and so forth) individually. ¾ CIRCLE: Creates a circle by picking the center point and point that lies on the circumference of the circle. The intent manager allows drawing circle in different ways. ¾ 3 TANGENT: Creates a circle tangent to the selected three reference entities. ¾ FILLET: Creates a circle tangent to the selected two reference entities. ¾ 3 POINT: Creates a circle by picking any three circumferential points. ¾ ELLIPSE: Creates a ellipse by clicking the center of the ellipse and drag the other point to complete the ellipse. ¾ FILLET: Creates a rounded intersection between any two entities. The size and location of the fillet depends on the pick locations. When a fillet is inserted between two entities, the system automatically divides two entities at the fillet tangency points. If we add the fillet between two nonparallel lines, the lines are automatically trimmed to the fillet. ¾ AXIS POINT: Using axis point option from the sketch menu to create an axis that is normal to the sketching plane. The depth of the axis is determined by the geometry of the feature and is similar to an axis of a cylindrical hole.
¾ DIMENSIONING: We can add our own dimensions to create the desired dimensioning scheme. User dimensions are considered as ‘STRONG’ dimensions by the system. As we sketch a section the system automatically dimensions the geometry .These dimensions are called weak dimensions. They appear in grey.Linear dimensioning is carried out to dimension a line or an entity. ¾ DIAMETER: To create a diameter dimension for arc or a circle the arc or the circle is double clicked and the middle mouse button to place the dimension. ¾ TRIM: Using this command we can trim two entities. Here we can click any two entities on the portion of the entity that we want to keep. Pro/ENGINEER trims two entities together. ¾ MIRROR: Mirror command is used to mirror the sketcher geometry about a sketched centerline. For example, we can create half of the section and then mirror it. Before mirroring make sure the sketch contains the centerline. Here we can select an entity or multiple entities to mirror.
2.1.2 MODELING TOOLS: Protrusion feature: Protrusion is the method of adding a solid material to the model that is, it can add material in a void or on an existing solid. Types of protrusion feature are:
1. Extrude-creates a solid feature by extruding a section normal to the section plane. 2. Revolve-creates a solid feature by revolving a section about an axis. 3. Sweep-creates a solid feature by sweeping a section about trajectory. 4. Blend-creates a solid feature by blending various cross section at various levels. ¾ EXTRUSION: Extrusion is the method of defining a volume by extruding the sketched cross section along an axis normal to the section plane. To define Extrusion first we should define the sketch plane in which we want to draw the cross section, and then we have to define the direction of Extrusion and the amount of Extrusion by various options. ONE SIDE: Adds the material in one side of the cross-section only. BOTH SIDE: Adds the material on both sides of the crosssection. BLIND: By this method we can directly specify the depth of Extrusion as a numerical value. 2 SIDE BLIND: This method is available for extrusion in both sides. ¾ CUT FEATURE: Cut is a method of removing solid material from the model.
CUT EXTRUDE: Removes a volume by extruding its section a normal to the section plane. SWEPT BLEND:A swept blend requires a trajectory and multiple sections. To define the origin trajectory of the swept blend, we can either sketch a curve or select a chain of datum curves or edges. ¾ PATTERN: A pattern allows us to make parametric copies of an existing feature. Because a pattern is parametrically controlled, we can modify it by changing pattern parameters, such as number of instance, spacing between instances and leader dimensions. All instances are by nature duplicates of the leader, changing a leader dimension updates all instances and vice versa. The pattern command only allows we to select a single feature, we can pattern several feature as if they were single feature by arranging them in a local group. 2.1.3 ASSEMBLY CONSTRAINTS: We can position one component with respect to the other components using assembly constraints. A placement constraint specifies the relative position of a pair of references. The followings are the placement provided by Pro/ENGINEER. And we are explaining the main constrains that are used to design the model: Mate Align Insert
Coord Sys Tangent Pnt On Line Pnt OnSrf Edge On Srf Default Fix ¾ MATE: We can use the mate constraint to position two planar surfaces or datum planes parallel and their normal pointing opposite to each other. If datum planes are mated their yellow sides face each other. ¾ ALIGN: We can use the Align constraint to make two planes coplanar (coincident and facing the same direction) two axes coaxial, or two points coincident. We can align revolved surface or edges. The yellow sides face the same direction instead of facing each other as when mated. ¾ INSERT: We can use the Insert constraint to insert one revolved surface into another revolved surface, making their respective axes coaxial. This constraint is useful when axes are unavailable or inconvenient for selection.
¾ ORIENT: We can use the Orient constraint to orient two planar surfaces to be parallel facing the same direction. It does not specify the offset. ¾ COORD SYS: We can use the Coord Sys constraint to place a component in an assembly by aligning its coordinate system with a coordinate system in the assembly ¾ PNT ON LINE: We can use the Pnt On Line constraint to control the contact of an edge, axis, or datum curve with a point. ¾ EDGE ON SRF: We can use in this constraint to control the contact of a surface with a planar edge. ¾ FIX: We can use the Fix constraint to fix the current location of the component that was moved or packaged. 2.1.4 CONSTRAINT ORIENTATION ASSUMPTIONS: After defining an align constraint between the axes of the hole and the bolt and ,for example, a mate constraint between the bottom face of the bolt and the top face of the plate, the system assumes at hired constraint.
The constraint controls rotation about the axes, thereby fully constraining the components. With the Pro/ENGINEER assumptions disabled, we can package drag a component out of a previously assumed position. And have it remain in the new position. The component automatically snaps back to the assumed position if Assumption check box ¾ MIRROR:DRAWING>tools>mirror We can use this command to create copies of draft and entities, unattached symbols, and unattached notes by mirroring them about to a draft line Select a draft line about which to mirror the entities. The system creates a copy of the selected entities as mirror image of the source entities. ¾ TRIM:DRAWING>tools>trim We can use this command to lengthen or shorten draft geometry. The system uses the geometry definition to find its intersection with the bounding entity. When we choose this command, PRO-E displays the trim menu. We can export solid model information about parts and assemblies in the following formats STL(Stereo lithography apparatus) RENDER, inventor, VRML, OpteraVis, Xpatch, MEDUSA, Catiafacets (also referred to as catia mock-up), and 3-D paint. STL is used for a variety of puposes,the primary one is rapid prototyping.
2.1.5 COMMON EXCHANGE SPECIFICATIONS: ¾ STEP FILES: Through STEP, we can exchange complete product definition between
manufacturing systems. The step format is organized as a series of documents(in STEP terminology, referred to as parts)with each part published separately application protocols (Aps)which reference generic parts, are produced to meet specific data exchange requirements for a particular application. ¾ IGES: When exporting assembly files to IGES, the System generates an IGES file with the suffix _asm appended to the name of the file. This is to prevent overwriting a part with an assembly file of the same name. When an assembly is exported to IGES , the structure and the output contents are specified. Select all levels which exports an assembly file with external references to all components as well as all the components to IGES files. It creates components parts and subassemblies with their respective geometry and external references. This option supports all levels of hierarchy. 2.1.6 CAPABILITIES & BENEFITS:
Complete 3D modeling capabilities.
Maximum production efficiency through automated generation of associative tooling design, assembly instructions, and machine code
Ability to simulate and analyze virtual prototypes to improve product performance and optimize product design
Ability to share digital product data seamlessly among all appropriate team members
Compatibility with myriad CAD tools — including associative data exchange — and industry standard data formats
2.2 ABOUT ANSYS ANSYS is a complete FEA simulation software package developed by ANSYS Inc-USA. It is used by engineers worldwide in virtually all fields of engineering. • Structural • Thermal • Fluid (CFD, Acoustics, and other fluid analyses) • Low-and High-Frequency Electromagnetics. Introduction to General Analysis Procedure in ANSYS Ansys is a high-performance finite element pre- and postprocessor for popular finite element solvers – allowing engineers to analyze product design performance in a highly interactive and visual environment. Ansys user-interface is easy to learn and supports many CAD geometry and finite element model files – increasing interoperability and efficiency. Advanced functionality within ansys allows users to efficiently mesh high fidelity models. This functionality includes user defined quality
criteria and controls, morphing technology to update existing meshes to new design proposals, and automatic mid-surface generation for complex designs with of varying wall thicknesses. Automated tetra-meshing and hexameshing minimizes meshing time while batch meshing enables large scale meshing of parts with no model clean up and minimal user input. • FEA & ANSYS Finite Element analysis, the core of Computer Aided Engineering dictates the modern mechanical industry and plays a decisive role in cost cutting technology. ANSYS the leading FEA simulation software, with its robust capabilities guides the Engineers to arrive at a perfect design solution. A PARTIAL LIST OF INDUSTRIES IN WHICH ANSYS IS USED: • Aerospace • Automotive • Biomedical • Bridges & Buildings • Electronics & Appliances • Heavy Equipment & Machinery • MEMS – Micro Electromechanical Systems • Sporting Goods
2.2.1 GENERAL ANALYSIS PROCEDURE This explains the general analysis procedure to be used to solve a simulation. Regardless of the physics of the problem, the same general procedure can be followed. Every analysis involves four main steps: • Preliminary Decisions • Preprocessing • Solution • Post processing ¾ PREPROCESSING CREATE THE SOLID MODEL A typical solid model is defined by volumes, areas, lines and keypoints. CREATE THE FEA MODEL Meshing is the process used to “fill” the solid model with nodes and elements, i.e., to create the FEA model. DEFINE MATERIAL Every analysis requires some material property input: Young’s modulus EX for structural elements, thermal conductivity KXX for thermal elements, etc. There are two ways to define material properties
Material library ¾ Individual properties Solution ¾ Define Loads There are five categories of loads • DOF Constraints • Concentrated Loads • Surface Loads Loads distributed over a surface, such as pressure or convections.
• Body Loads • Inertia Loads ANSYS POSTPROCESSORS: POST1, the General Postprocessor, to review a single set of results over the entire model. POST26, the TimeHistory Postprocessor, to review results at selected points in the model over time. Mainly used for transient and nonlinear analysis. 2.2.2 STRUCTURAL ANALYSIS: Structural analysis is probably the most common application of the finite element method. The term structural (or structure) implies not only civil engineering structures such as bridges and buildings, but also naval,
aeronautical, and mechanical structures such as ship hulls, aircraft bodies, and machine housings, as well as mechanical components such as pistons, machine parts, and tools. The primary unknowns (nodal degrees of freedom) calculated in a structural analysis are displacements. Other quantities, such as strains, stresses, and reaction forces, are then derived from the nodal displacements. Structural analysis is available in the following ANSYS programs. ¾ ANSYS/Multiphysics ¾ ANSYS/Mechanical ¾ ANSYS/Structural ¾ ANSYS/Professional 126.96.36.199 TYPES OF STRUCTURAL ANALYSIS STATIC ANALYSIS Used to determine displacements, stresses, etc. under static loading conditions which includes both linear and nonlinear characteristics. Nonlinearities can include plasticity, stress stiffening, large deflection, large strain, hyper elasticity, contact surfaces, and creep. 188.8.131.52 STEPS IN A STRUCTURAL ANALYSIS ¾ CREATION OF GEOMETRY: This can either be created within ANSYS or imported. The following points are to be carefully considered in model creation.
Sufficiently model the stiffness of the structure. Add details to avoid stress singularities (e.g. filets). Exclude details not in region of interest (e.g. exclude small holes) . Add details to improve boundary conditions (e.g. apply pressure to an area rather than using concentrated load). ¾ ELEMENT TYPE Most ANSYS element types are structural elements, ranging from simple spars and beams to more complex layered shells and large strain solids. The nodal DOF’s may include: UX, UY, UZ, ROTX, ROTY, and ROTZ. Most types of structural analyses can use any of these elements.
Beam 4 Beam 188
Quadratic Plane82 Plane2
MATERIAL PROPERTIES In certain ID or 2D problems, the second or third parameters or both are specified through the Real Constants or Section properties command. For e.g. in a beam problem, we can specify the length in the model, but the cross section parameters are specified in the Sections properties, Similarly, thickness for a shell element is specified in the Real Constants dialog box. To define real constants: Choose Preprocessor Real Constants from the main menu. In the Real Constants dialog box, click Add. Then enter the specified real constant value of the material selected. ¾ DEFINE LOADS Structural loading conditions can be: DOF Constraints - Regions of the model where displacements are known. Concentrated Forces - External forces that can be simplified as a point load. Pressures - Surfaces where forces on an area are known.
¾ DISPLACEMENT CONSTRAINTS This is used to specify where the model is fixed (zero displacement locations). It can also be non-zero, to simulate a known deflection. To apply displacement constraints: Choose Solution
Displacement ¾ Preferences ¾ Preprocessor ¾ Solution ¾ Analysis Type ¾ Define Loads ¾ Settings ¾ Apply ¾ Structural ¾ Displacement ¾ On Lines ¾ On Areas ¾ On Keypoints
¾ On Nodes ¾ On Node components ¾ Symmetry B.C. ¾ Antisymm B.C. Pick the desired entities in the graphics window. Then choose the constraint direction. Value defaults to zero. ¾ CONCENTRATED FORCES Force is a point load, applied on a node or keypoint, specifying the force magnitude and direction of force. Choose Solution Define Loads Apply
Force/Moment from Main Menu. When we delete solid model loads, ANSYS also automatically deletes all corresponding finite element loads. ¾ REVIEWING RESULTS Gives a quick indication of whether the loads were applied in the correct direction.Legal column shows the maximum displacement, DMX.We can also animate the deformation.To plot the deformed shape Choose General Postproc Plot Results
Choose Plot CtrlsÆAnimate ÆDeformed shape ¾ STRESSES:
The following stresses are typically available for a 3-D solid model.
Component Stresses - SX, SY, SZ, SXY, SXZ (global
Cartesian direction by default.
Principal Stresses - S1, S2, S3, SEQV (von Misses),
SINT (Stress intensity). Best viewed as contour plots, which allow us to quickly locate "hot spots" or trouble regions. Nodal solution: Stresses are averaged at the nodes, showing smooth, continuous contours. Element solution: No averaging, resulting in discontinuous contours. ¾ TO PLOT STRESS CONTOURS: General Postproc * Plot Results * Contour Plot Nodal Solu General Postproc
* Plot Results
* Contour Plot * Element
Solu We can also animate stress contours : Plot Ctrls > Animate> Deformed Results... 2.2.3 BENEFITS:
Reduce time and engineering analysis cost through highperformance finite element modeling and post-processing
The industry's broadest and most comprehensive CAD and CAE solver direct interface support
Reduce overhead costs of maintaining multiple pre- and postprocessing tools, minimize "new user" learning curves, and increase staff efficiency with a powerful, intuitive, consistent finite element analysis environment
Open-architecture design and customization functionality allows to Ansys fit seamlessly in any environment
Reduce redundancy and model development costs through the direct use of CAD geometry and legacy finite element models
Simplify the modeling process for complex geometry through high-speed, high-quality automeshing, hexa-meshing and tetrameshing
eliminating the need to perform manual geometry clean up and meshing with Batch Mesher technology
CHAPTER 3 TRUCK AND CHASSIS 3.1 DIFFERENT PARTS OF A TRUCK:
Fig3.1 Different parts of a truck The different parts of a truck are: 1.Body 2.Axle 3.Chassis frame 4.Transmission 5.Engine 6. Cab.
¾ BODY: Specific body structures such as flatbeds, standard vans, box vans, dump-truck deep-beds, tankers, concrete mixers etc. permit the economical and efficient transportation of a wide variety of goods and materials. Connection between body and load-bearing chassis frame is effected in part by means of auxiliary frames. ¾ AXLE: An axle is a central shaft for a rotating wheel or gear. In some cases the axle may be fixed in position with a bearing or bushing sitting inside the hole in the wheel or gear to allow the wheel or gear to rotate around the axle. In other cases the wheel or gear may be fixed to the axle, with bearings or bushings provided at the mounting points where the axle is supported. ¾ CHASSIS FRAME: The chassis frame is the commercial vehicle’s actual load bearing element. It is designed as a ladder type frame, consisting of side and cross members. The conventional chassis frame, which is made of pressed steel members, can be considered structurally as grillages. The chassis frame includes cross-members located at critical stress points along the side members. To provide a rigid, box-like structure, the cross-members secure the two main rails in a parallel position. The cross-members are usually attached to the side members by connection plates.
¾ TRANSMISSION: Small trucks use the same type of transmission as almost all cars which have either an automatic transmission or a manual transmission with synchronizers. Bigger trucks often use manual transmissions without synchronizers which are lighter weight although some synchronized transmissions have been used in larger trucks. Transmissions without synchronizers require either double clutching for each shift, (which can lead to repetitive motion injuries,) or a technique known colloquially as “floating,” a method of shifting which doesn’t use the clutch, except for starts and stops. ¾ ENGINE: An engine is something that produces an effect from a given input. ¾ CAB: The cab is an enclosed space where the driver is seated. There are a variety of cab designs available depending on the vehicle concept. In delivery vehicles and vans, low, convenient entrances are an advantage, whereas in long-distance transport space and comfort are more important. The type of cab configurations are cab-over-engine (COE) and cab-behindengine. 3.2 FUNCTION OF CHASSIS FRAME: The chassis frame is the commercial vehicle’s actual load bearing element. It is designed as a ladder type frame, consisting of side and
cross members. The choice of profiles decides the level of torsional stiffness. Torsionally flexible frames are preferred in medium and heavy duty trucks because they enable the suspension to comply better with uneven terrain. Torsionally stiff frames are more suitable for smaller delivery vehicles and vans. Critical points in the chassis-frame design are the side-member and the cross-member junctions. Special gusset plates or pressed crossmember sections form a broad connection basis. These junctions are riveted, bolted and welded. The conventional chassis frame, which is made of pressed steel members, can be considered structurally as grillages. The chassis frame includes cross-members located at critical stress points along the side members. To provide a rigid, box-like structure, the cross-members secure the two main rails in a parallel position. The cross-members are usually attached to the side members by connection plates. The joint is riveted or bolted in trucks and is welded in trailers. When rivets are used, the holes in the chassis frame are drilled approximately 1/16 in larger than the diameter of the rivet. The rivets are then heated to an incandescent red and driven home by hydraulic or air pressure. The hot rivets conform to the shape of the hole and tighten upon cooling. An advantage of this connection is that it increases the chassis flexibility. Therefore, high stresses are prevented in critical area. The side- and cross-members are usually open-sectioned, because they are cheap and easily attached with rivets.
3.3 PARTS OF A TRUCK CHASSIS FRAME:
Fig 3.2 Parts of a truck chassis frame The different parts of a conventional truck chassis frame are: 1.Side members 2.Cross members
3. Gusset plates or connection plates.
3.4 RIVETING OPERATION ON TRUCK CHASSIS: A monorail shall be provided above the operating places and the trolley compiled with the balancer shall be hung down from the monorail. The generator shall be installed at the place where it will be free from troubles and operation. The high pressure steel pipe shall be arranged from the generator to the center upper portion of operating position, then high pressure hose shall be connected between the pipe end and riveter the piping shall be fixed at near by columns or supporting beams, with clamps for protection against vibration the hose shall be fixed with spring bands in order to flexure; however its fixing shall not affect the operation of riveter.
Fig 3.3 Installation of a Riveter
Fig 3.4 Riveting Operations on a truck chassis ¾ ADVANTAGES OF COLD RIVETING: 1. The heating equipment and its operator are unnecessary. Handing of rivet is easy, accordingly. 2. In case of riveting, if its rivet is longer in length or irregular in hole diameter, the rivet will be fully expanded in the hole, then the rivet head will be formed; therefore it makes no looseness in cooling, sealing or against vibrations. 3. Caulking is not necessary because no extra tension is added to the rivet.
3.5 LOADS ON CHASSIS FRAME : All vehicles are subjected to both static and dynamic loads. Dynamic loads result from inertia forces arising from driving on uneven surfaces. Static loads are as follows : Static load of stationary vehicle, braking, acceleration, cornering, torsion, maximum load on front axle, maximum load on rear axle. Loads acting in the frame cause bending or twisting of the side and the cross-members. Symmetric loads acting in the vertical direction predominantly cause bending in the side members. Vertical loads additionally arise from lateral forces acting parallel to the frame’s plane, e.g. during cornering. Loads acting in the plane of frame cause bending of the side members and of the cross-members.
o SPECIFICATIONS OF 1613H
Fig 3.5 Model-1613H
3.6 MATERIAL DATA: Table 3.1 Material Data
HSLA Steel to Ashok Leyland Standard for ALMDV Models Having Young’s Modulus (E) 2.6*105 N/mm2 and Poisson’s MATERIAL
Ratio (ν) 0.3.
MODELLING AND MESHING OF TRUCK CHASSIS
4.1 PRO-E MODEL OF THE DESIGNED CHASSIS
Fig 4.1 Pro-E Model of Chassis
4.2 MESHED MODEL OF THE CHASSIS:
Fig 4.2 Meshed Chassis
Fig 4.3 Zoomed View of Meshed Model
CHAPTER 5 STRESS ANALYSIS 5.1 Load Applied On the Model:
Fig 5.1 Load Applied
Fig 5.2 Zoomed View of Applied load
5.2 STRESS DISTRIBUTION AT JOINT AREAS 5.2.1 Stress distribution across joint 1
Fig 5.3 Nominal Loading at Joint 1
Fig 5.4 Stresses at Maximum Load Condition on Joint 1
5.2.2 Stress distribution across joint 2
Fig 5.5 Stress Distribution On Nominal loading In Joint 2
Fig 5.6 Stress Distribution at Joint 2 on Maximum Load condition
5.2.3 Stress distribution across joint 3
Fig 5.7 Stress Distribution on Nominal loading In Joint 3
Fig 5.8 Stress Distribution at Joint 3 on Maximum Load condition
5.2.4 Stress distribution across joint 4
Fig 5.9 Stress Distribution on Nominal loading In Joint 4
Fig 5.10 Stress Distribution at Joint 4 on Maximum Load condition
5.2.5 Stress distribution across joint 5
Fig 5.11 Stress Distribution on Nominal loading In Joint 5
Fig 5.12 Stress Distribution at Joint 5 on Maximum Load condition
5.2.6 Stress distribution across joint 6
Fig 5.13 Stress Distribution on Nominal loading In Joint 6
Fig 5.14 Stress Distribution at Joint 6 on Maximum Load condition
CHAPTER 6 RESULTS AND DISCUSSION From the analysis performed the maximum stress was found to be at joint area 5 the respective graphs shown below clearly signifies that at the maximum loading condition the stress was found to be 151.98 N/mm. Table 6.1: Stress distribution across the joints J o i n t a r e a n u m b e r
S t r e s s
S t r e s s
N o m i n a l
M a x i m u m
l o a d i n g
l o a d i n g
N / m m
N / m m
1 5 1
1 3 3
1 3 3
1 1 7
1 5 2
1 4 4
Graph 6.1 Stress distributions at Nominal Loading 70 60
60 50 43
40 Nominal loading
30 20 10 0 1
Graph 6.2 Stress distributions at Maximum loading 160 STRESS (N/MM^2)
The 140 presence120 of
144 area was due to the reason for maximum stress in the joint 133
117 plate (Connecting plate) and the gap found between the gusset
side member as shown below. 80
60 40 20 0 1
Fig 6.1 Gap at Joint 5
SUGGESTION To reduce the stress at the joint area 5 local plates can be introduced as shown below.
Fig 6.2 Introduction of local plates at joint 5
CHAPTER 7 CONCLUSION From the stress analysis performed, the maximum stress acting on the truck chassis was found to be at joint 5(151N/mm2 ) and local plates can be introduced to reduce the stress at the joint area. Furthermore, the stress value of 151N/mm2 was found to be considerably lower than the allowable stress of the material (288 N/mm2). Thus, a suitable material can
be selected and consequently a reduction in the overall weight of the chassis can be achieved.
REFERENCES: • Stress analysis of a truck chassis with riveted joints Finite Elements in Analysis and Design, Volume 38, Issue 12, October 2002, Pages 1115-1130 Ciçek Karaolu and N. Sefa Kuralay • Automotive handbook, BOSCH, 5th Edition, Page 730-736 • Strength of Materials and Structures, 2nd Edition, Page 55-91, J. Case and A. H. Chilver •
Stress intensity factor and load transfer analysis of a cracked riveted lap joint Materials & Design, Volume 28, Issue 4, 2007, Pages 1263-1270
• Stress intensity factors in riveted steel beams Engineering Failure Analysis, Volume 11, Issue 5, October 2004, Pages 777-787 J. Moreno and A. Valiente